Feature request: floating point values for custom interpolation field

The custom interpolation field is great for interpolating slant values. For example, I’m working on a type family with a 17.5° oblique. I’m going to interpolate something in between and extrapolate a backslanted version. But the custom field only accepts integer values. Of course there’s an easy fix—just multiply the values by ten so there isn’t a decimal. But it would be nice if I could just use a floating point value.